GeoGreen Sealant (Caulk)
Maybe caulking and sealants are not the sexiest part of green building, but as my green architect friend pointed out, good, efficient glazes and sealants are absolutely crucial for a green home. If you have a sealant that performs poorly in certain parts of the year or cracks after a few years, your home dramatically loses heat and energy efficiency, increasing your bills and your carbon footprint.
In addition, you want to choose sealants that have no or very low VOCs, thereby increasing your indoor air quality and reducing your impact on the environment.
Some sealants also have hazardous and/or ozone-depleting ingredients, so naturally you want to avoid those too.
Ideally, choose caulking and sealants with reusable containers for lowest environmental impact.
In my searching, I found GeoGreen Siding, Window & Door Sealant as a good balance of all these considerations. This material remains flexible permanently and won't crack or shrink, giving it great durability for long-lasting effective sealing. In addition, it meets the LEED standards for very low VOCs, and adheres very well to the types of materials used often in green buildings (fiber cement board, and others).
Always compare the products available to you for best results, but this sealant is a great place to start.